User Guide

2.1.2 ECP mode

In the ECP mode, data can be received at high speed as data transactions are carried

out on a bi-directional data bus. As data and commands are differentiated by control

signals, and bi-directional communications can be carried out, switching to another

mode is not necessary when the data transfer direction is switched.

The data bus direction changes from forward data transfer to reverse data transfer in

response to the falling edge of the AckReverse signal from the printer.

Alternatively, the data bus direction changes from reverse data transfer to forward

data transfer in response to the rising edge of the ReverseRequest signal from the

printer.

4-9

BJC-8500

Part 4: Technical Reference

Data=High

Command=Low

Reverse Phase Forward

Phase

Forward Phase Forward to

Reverse

35msMax

0MIN

1284Active

AckReverse

HostBusy

XFlag

(Select)

HostClk

PeriphClk

PeriphBusy

PeriphRequest

ReverseRequest

Input Output Valid Valid Input

Data 1 to 8

Figure 4-9 Interface Timing (ECP Mode)